I have a little boar, Marmite, who lives alone, he was guessed to be at 2 years old and i’ve had him for over a year now, he was adopted from Pets at Home, as an 'aggressive piggy' that couldn’t live with other piggies. His ears are all ripped from previous fights, and from what i guess he’s just been passed from home to home as he had at least 3 homes through Pets at home previously to me, where he was placed with other pigs and just ended up fighting, hence why he was deemed aggressive. I decided he was more suited to a side by side living arrangement just because of the way he was around other piggies he wont settle with them, so he lives in his own cage, just under my other two boys, so he can still smell and wheek with them, and every day i let my boys run around the floor and they say hello to him sort of thing and they chase each other up and down the side of the cage, and that keeps him happy, but as soon as that cage wall isn’t there Marmite just gets really scared and panics again so thats why i find he’s just happier by himself but with someone to talk to
It really is one of those things where it just depends on the pig, and you don’t know how they react until you try them with another pig. So as mentioned above, the best thing is to try boar dating, and look for just one other piggy companion, as 3 don’t really get on

Also, another thing is with older piggies they usually get on best with babies, and lots of rescues end up with pregnant piggies so they may have some little baby boars available, this is usually just because the relationship between the pigs turns into an daddy and baby kind of roll so there is less chance of fighting, but that doesn’t mean your piggy wouldn’t get on with an older piggy too.